With　continuous　minimization　of　nano　devices,　the　dimensions　of　metallic　materials　used　in　nanodevices　decrease　to　a　few　nanometers.　Understanding　the　structural　stability　and　deformation　behavior　of　these　small-sized　metallic　materials　is　important　for　their　practical　applications.　Here　we　report　our　atomic　resolution　observation　of　the　deformation　processes　of　Ag　nanowires　with　widths　of　3　nm.　The　nanowires　under　tension　experienced　plastic　deformation　via　partial　dislocation　activities,　which　led　to　deformation　twinning　in　and　homogeneous　elongation　of　the　nanowires,　and　surface　atom　diffusion　that　reduced　the　nanowires＇　width　but　did　not　contribute　to　the　nanowire　elongation.　The　diffusion　of　surface　atoms　was　initiated　at　surface　steps　introduced　by　the　partial　dislocation　activities,　leading　to　fracture　of　the　nanowires　with　relatively　low　homogeneous　elongation.